Method and system of forming a composite laminate

ABSTRACT

A method and associated system for forming composite materials is presented, including providing a composite charge having applied release films to top and bottom surfaces and positioned on a contoured forming tool such that a portion of the composite charge over hangs a second upper surface of forming tool. A fairing bar abuts the forming tool that has an uppermost surface positioned above the second upper surface of the forming tool. The combination of the positioning of the fairing bar and the use of release film in contact with the composite charge allows the composite charge to conform to the contoured forming tool without bridging or wrinkling the composite charge when a forming membrane and applied vacuum are used.

TECHNICAL FIELD

This disclosure generally relates to systems and processes for forming alaminate composite, particularly using a complex shaped and contouredforming tool.

BACKGROUND

Formed composite parts are commonly used in applications, such asaircraft and vehicles, where lightweight and high strength are desired.Fabricating composite parts, for example a ply-by-ply airplane wingstringer, requires the use of a lay-up tool (also known as a base tool,forming tool or mandrel) on which layers of composite materials orpre-cure lamina are hand formed or laid one ply at a time. Theseapplications can utilize complex contoured finished parts or channelsthat must be formed and then cured. Historically, complex contouredcomposite structures have entailed extensive hand labor to form themprior to curing. Typically, the pre-impregnated composite fiber plies(“pre-pregs”) such as epoxy impregnated carbon fiber laminates are laidby hand or by a machine over a tool or mandrel. Once the desired numbersof layers are placed on the tool, the composite laminate is bagged andcured in a curing apparatus, such as an autoclave. Unfortunately,laying-up of a composite charge over a complex shaped forming toolcreates several challenges and must be done manually by hand. It is timeconsuming and expensive to perform ply and ply lay-up.

One forming method, known as drape forming, uses vacuum bagging. Drapeforming has been used successfully to form composite parts where theparts being formed are formed over tools that only have male radius.This method involves heating a flat laminate pre-preg composite blank orcharge and forcing it around a forming tool with the use of a vacuumbag. However, this method has met with limited success on tools withfemale radius or more complex shapes.

Vacuum bag drape forming of such parts can often result in wrinklingand/or pinching of the plies. Wrinkles occur because some laminate pliesare in compression when bent or urged over the forming tool, and bucklewhen there is no constraint on the bending portion to preventout-of-plane-buckling. Similarly, on long flange parts, slip resistancebetween the plies during bending becomes too great, and inner pliesbuckle. Buckling or wrinkling of the plies also occurs over tools thatare curved or contoured, or have joggles along their length. Even slightcontours of a radius on the order of thousands of inches is enough toinitiate wrinkles.

In particular, when using a Z-shaped tool, the male and female radiicreate challenges in the hot drape process as the charge may only formover the male radius. As the composite pre-preg charge is bent over theforming tool, if the length of the flange is too long or slip resistancebetween the plies is too great, out-of-plane-buckling of the laminatewill occur. This results in the use of a time consuming two-step processwhere a special tool is used to form the male radius and then separatelyto form the female radius, typically using hand lay-up techniques.

Although there has been limited success with use of release filmsapplied to the base tool, because these films have inherently have lowtack properties they do not provide a stable and secure surface for thelay-up of the plies of composite pre-preg material. This can result inslower than desired laydown rates and an increase in scrapped parts.

Accordingly, there is a need for improved hot drape systems and methodsof laying-up composite plies over a complex and contoured forming toolthat avoids or minimizes hand lay-up processes and wrinkling that isexperienced with prior known methods.

SUMMARY

The disclosed embodiments provide a method for forming compositematerials where a composite charge having a layer of release filmapplied to the upper and lower surfaces is used in a lay-up system.

A first portion of the composite charge is positioned on a first uppersurface of a forming tool such that a second portion of the compositecharge overhangs a second upper surface of the forming tool. The firstupper surface of the forming tool is higher in height that the secondupper surface. The height of the surfaces is measured from a commonbottom surface. A fairing bar is positioned to abut the forming tool,where the fairing support has an uppermost surface and is positionedsuch that an uppermost surface is above the second upper surface of theforming tool. A forming membrane is applied over the composite charge,release film, forming tool and fairing bar and is sealed around aperipheral edge of the lay-up system. Vacuum is applied to the lay-upsystem to cause the forming membrane to conform to the forming tool suchthat the second portion of the composite charge is brought into contactwith the second upper surface of the forming tool such that the formingmembrane is conformed to and contacts the fairing bar before the formingmembrane conforms the second portion of the composite charge to thesecond upper surface. In some circumstance it is desirable to heat thecomposite charge before and or during the evacuation of formingmembrane. Stated differently, the vacuum causes the forming membrane toconform to the forming tool such that a portion of a laid-up compositecharge is brought into contact with a surface of the forming toollocated between the first and second upper surfaces and a remainingportion of the composite contacts and slides along the second uppersurface.

Application of the vacuum causes the composite charge to conform asegment of the second portion over an outer radius of the forming tool.A mechanical force is applied to the second portion of the compositecharge to conform the composite charge to an inner radius of the formingtool. The mechanical force can be applied using an urging deviceincludes at least one of a flexible tip, a spring board, a featherboard, an elastic fairing, a compressible material, a pivoting pad, anda spring-loaded pad. In one preferred method the forming of thecomposite charge to both an inner and outer radius of the forming tooloccurs where the forming membrane dose not prevent the second portion ofthe composite charge from sliding along the second upper surface of theforming tool to conform to the inner radius. Stated differently, thefairing bar configuration and positioning relative to the forming toolprevents the forming membrane from applying a downward force on thesecond portion of the composite charge that prevents the second portionfrom sliding or slipping along the second upper surface of the formingtool. To achieve the necessary degree of slippage of the second portionof the composite charge it may also be advantageous to apply releasefilm to the second upper surface of the forming tool prior topositioning the composite charge on the forming tool such. In thissituation the release film on the bottom surface of the composite chargewould be in sliding contact with release film on the second uppersurface of the forming tool.

A lay-up system for forming composite materials is also disclosed thatincludes a forming tool comprising a first upper surface, a second uppersurface, a bottom surface, an outer radius and an inner radius, wherethe forming tool has a first height measured from the first uppersurface to a bottom surface and a second height measure from the secondupper surface to the bottom surface. The system further includes afairing bar abutting the forming tool that has a height greater than thesecond height of the forming tool, where the height of the fairing baris measured from an uppermost surface to a lower most surface. Acomposite charge is part of the lay-up system that has an upper surfaceand a lower surface, each having an applied layer of release film. Thecomposite charge also has a first portion that will contact the firstupper surface of the forming tool and has a second portion that willoverhang the second upper surface of the forming tool. A formingmembrane is used to overlay the composite charge, release film, formingtool and fairing bar such that a vacuum system will draw a vacuumsufficient to cause the forming membrane to conform to the forming toolsuch that the portion of the composite charge over hanging the second isbrought into contact with a second upper of the forming tool after theforming membrane is conformed to and contacts the fairing bar.

The forming tool used in the system of this disclosure can be complex inshape having at least an outer radius and an inner radius, where theouter radius is contiguous with the first upper surface of the formingtool and the inner radius is contiguous with the second upper surface. Arelease film of fluorinated ethylene-propylene can be advantageouslyused along with a forming membrane made from silicone. The second uppersurface of the forming tool can also contain a layer of release film toassist in the conformation of the second portion of the composite chargeto the female or inner radius of the forming tool.

The features, functions, and advantages that have been discussed can beachieved independently in various embodiments or may be combined in yetother embodiments, the further details of which can be seen withreference to the following description and drawings.

BRIEF DESCRIPTION OF THE FIGURES

The present disclosure will become more fully understood from the moredetailed description presented below and the accompanying drawings whichare presented by way of illustration only, and thus, are not limitationsof the present disclosure, and wherein:

FIG. 1 is a schematic illustration of a side view of a known lay-upsystem for use with contoured forming tools;

FIG. 2 is an illustration of the known lay-up system of FIG. 1 after aforming membrane is applied and evacuation begins;

FIG. 3 is an illustration of the known lay-up system of FIG. 2 showingthe application of mechanical force while a vacuum is applied in anattempt to eliminate bridging of the composite charge in the inner orfemale radius;

FIG. 4 is an illustration of the lay-up system of this disclosure afterthe composite charge is positioned on the forming tool and the formingmembrane is placed over the composite charge, forming tool and a fairingbar;

FIG. 5 is an illustration of the lay-up system of FIG. 4 where thevacuum is first applied;

FIG. 6 is an illustration of the lay-up system of FIG. 4 later in theforming process where the second portion of composite charge isconforming to the inner radius of the forming tool as a mechanical forceis being applied;

FIG. 7 is an illustration of the lay-up system of FIG. 4 where thecomposite charge has conformed to the forming tool including the outerand inner radii without bridging;

FIG. 7a is a schematic representation of two possible Z-shaped tools orformed composite parts that can be used in or produced by, respectively,the lay-up system of the present disclosure;

FIG. 8 is an illustration of the formed composite from the system ofFIG. 4 being added to a curing tool and then placed in a curingapparatus;

FIG. 9 is an illustration of a perspective view of an aircraft that mayincorporate one or more composite laminates manufactured in accordancewith one or more embodiments disclosed herein;

FIG. 10 is an illustration of a flow diagram of an embodiment of anaircraft production and service method of the disclosure; and

FIG. 11 is an illustration of a functional block diagram of an aircraft.

Corresponding parts are marked with the same reference symbols in allfigures.

DETAILED DESCRIPTION

A first step common to the processes and systems described in connectionwith various embodiments of the invention described here involvesproviding a suitable forming or lay-up tool. Existing forming tools canbe used or in some circumstances a forming tool is fabricated torepresent the tooled surface of the desired part, for example anairplane wing stringer or other primary or secondary structures, namely,Z-shaped beams, I-beams, hat stiffeners, C-channels, J-stiffeners,blade-stiffeners, floor-beams, ribs, frames, or spars. Fabricationand/or construction of forming tools are known to those skilled in theart and therefore such details need not be repeated here. When theforming tool has a complex shape with contours, for example a Z-shapedbeam, it becomes more challenging to conform a laminate composite (alsoknown as a composite charge) to the forming tool without wrinkling orthe use of time consuming hand lay-up procedures.

To illustrate some of the challenges with the current methods of formingcomplex composites FIGS. 1-3 present step-by-step cross-sectional viewsof a prior art vacuum bag forming system for forming compositematerials. A composite charge 20 is placed over a forming tool 10, Asexemplified, the tool 10 is a Z shaped forming tool having an outerradius 44 and an inner radius 46. Such a forming tool can be used tomanufacture a composite Z-shaped beam or spar. It will be appreciatedthat the composite charge may be any suitable material for formingcomposite parts, including, without limitation, dry fabric or pre-pregplies. The tool 10 rests upon or is linked to a vacuum base. The vacuumbase, tool 10, and composite charge 20 are covered by a vacuum bag ormembrane 24.

During forming of the composite charge 20 over the forming tool 10, thecharge 20 is heated and air is evacuated from beneath the vacuum bag 24causing the membrane 24 of the vacuum bag to be drawn down and conformto the tool 10 and to fairing bar 26. (see FIG. 2). This causes a firstportion of the composite charge 22 to be forced down against the firstupper surface 40 of tool 10. Portion 21 of the composite charge 20overhangs the second upper surface 42 of the forming tool 10, As shownin FIG. 2, the application of the heat and vacuum causes the laminateplies in the overhanging portion 21 and in first portion 22 of thecomposite charge 20 to be held in a non-slip abutment against the firstupper surface 40 and the second upper surface 42 of the forming tool,respectively. The forming membrane 24 exerts a downward pressure on thetwo portions at the two surfaces holding the composite charge so thatthere is relatively little slippage along the two upper surfaces of theforming tool. The tool has a male or outer radius 44 and a female orinner radius 46. Because of the downward pressure 48 exerted by theforming membrane while a vacuum is being drawn, the overhanging portion21 cannot conform to the female radius 46 resulting in an undesirablebridging 49 or non-conformance to the inner radius by the second portionof the composite charge. Even with applied mechanical force 50 thecomposite charge is unable to completely conform to the female radiusresulting in both wrinkling and bridging 49 of the overhanging portion21 near, but not conformed to, the female radius 46. (see FIG. 3).Forcing the composite charge into the female radius with a hand toolwill further exasperate the unwanted wrinkling.

Therefore, an unmet need exists for a composite forming method andsystem that forms laminate charges using forming tools with contours,joggles, or long flanges, without out-of-plane buckling of the laminateplies.

Starting with reference to FIG. 4, an exemplary embodiment of thepresent disclosure is described in detail using, for example, a Z-shapedforming tool 10 as part of lay-up system 100. The forming tool has afirst upper surface 40 and a second upper surface 42. The first uppersurface has a first height 58 measured from the bottom surface 72 andthe second upper surface 42 has a second height 59 likewise measuredfrom bottom surface 72. The first and second upper surfaces 40 and 42are generally facing upwards and away from the tool bottom 72. Theorientation of these upper tool surfaces, of course, is a function ofthe complexity and contours of forming tool itself. In the exemplifiedZ-shape forming tool discussed herein the two upper surfaces aregenerally parallel to each other and to the bottom surface, however,non-parallel surfaces could also be employed. The forming tool 10 alsohas a male radius 44 and a female radius 46. For illustration purposes,all the figures schematically illustrate a small radius of curvaturelocated at the intersection or corner 44, 46 of the horizontalrelatively flat surfaces 40 & 42 and a vertical relatively flat surface47 and the relationship of the flat surfaces is about 90 degrees. Theradius of the corners 44 and 46 could range from about 0.125 inch toabout 0.5 inch and the relative angle between the flat surfaces thattransition into the radii of curvatures could be in the range of fromabout 60 degrees to about 120 degrees. In other words the transitionfrom surface 40 to surface 47 and from surface 47 to surface 42 coulddefine a curve or radius of a circle, i.e., the radius of curvature.Reference is made to FIG. 7a that illustrates two possiblecross-sectional shapes for a Z-shaped forming tool or resultantcomposite part.

Once the forming tool is in a ready position, an optional release film53 be placed on the second upper surface 42 such that it will contact aportion of release film 52 on the bottom surface of composite charge 20.When the optional release film 53 is used, vacuum can be used todrawdown the release film 53 to the second upper surface 42 of theforming tool 10 to hold the release film place and to conform it to theshape of the forming tool. This will provide a release film-to-releasefilm interface for the second portion 81 of the composite charge 20 whenthe second portion is contacted with the second upper surface 42 of theforming tool. Preferably, the release film used in the lay-up system ofthis disclosure is of a composition that is acceptable to be used incontact with uncured pre-preg material and provides one or morenon-sticky or low tack surfaces. For example, such a release film ispreferably composed of fluorinated ethylene-propylene (FEP) and selectedso as not to adversely affect the resin content and/or resin-to-fiberratio of the composite charge used in the lay-up method. Other types ofrelease films can be used, including, but not limited to,polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE),Polyvinyl Fluoride (PVF) and TOOLTEC® (reinforced PTFE coated fiberglasswith adhesive). The release films applied to the composite charge 20 canbe the same or different, and the release film 53 applied to the formingtool can be the same or different as the other applied release films 52.FIG. 4 shows schematically the use of three release films. The releasefilms 52 and 53 can have a thickness in the range of from about 0.002 toabout 0.005 inches.

The composite charge 20 is positioned on the forming tool 10 such that afirst portion 80 of the composite charge 20 overlays the first uppersurface 40 of the forming tool 10 and a section portion 81 overhangs thesecond upper surface 42. The composite charge 20 has release film 52applied to both the top and bottom surfaces of the composite charge. Afairing bar 55 abuts the forming tool 10 and is configured in the lay-upsystem 100 such that the uppermost surface 70 is higher than the secondupper surface 42. The height 56 of the fairing bar is measured from thelowermost surface 71 to the uppermost surface 70. The second portion 81of the composite charge is sized and positioned such it will not comeinto contact with the fairing bar 55, but will conform to the secondupper surface of the forming tool. The fairing bar can have an uppermostsurface 70 that is about the same or less than the height 58. Comparedto forming tool 10, faring bar 55 can be manufactured out of alightweight and inexpensive materials, provided the material canwithstand a temperature of up to 200° F. and the pressures involved inthe vacuum forming process.

Heating and/or warming of the composite charge can occur prior to theforming of the composite charge onto the forming tool. Heating/warmingof the composite charge allows it to be more easily conformable to theforming tool as opposed to a composite charge at ambient or roomtemperature. Heating can be accomplished using infrared lamps,conventional light bulbs, or any other known heating techniques. Heatingof the composite can continue during the forming process. Depending onthe composition of the composite charge, the temperature of thecomposite charge can be raised to about less than or equal to 200° F.The temperature of the composite charge can be measure in anyconventional manner, such as, with attached thermocouples.

Once the composite charge is in the desired position a forming membrane24 is applied to cover the forming tool, release film, the fairing barand composite charge. The forming membrane is preferably composed ofsilicone, however, other known membranes suitable to vacuum forming canbe used, such as, polyvinyl alcohol or nylon based films. Once theforming membrane is in place, the end portions 85 are sealed with aseal, which preferably comprises a butyl rubber or other common vacuumbag sealant tape applied to both the lay-up system perimeter and theunderside of the forming membrane 24. Alternatively, an elastomer bladeseal could be used to provide a reusable and easily releasable seal. Theseal holds end portions 85 of the forming membrane at or near theperimeter edge of the lay-up system 100 in such a manner that when avacuum is drawn in the direction of arrows 200 this causes the formingmembrane to be drawn downward such that the first portion 80 of thecomposite charge is force downward and conforms to the first uppersurface of the forming tool as illustrated in FIG. 5.

Although a number of methods can be used to draw a vacuum to cause theforming membrane to conform to the shape of the tool surface, apreferred approach is to operatively couple a vacuum source to thelay-up system in a known manner so as to operate the vacuum source anddraw or pull a vacuum through channels located on an underside of theforming tool or lay-up system base. These channels would be in fluidcommunication with holes or other orifices extending upwards within anarea inside a perimeter defined by the seal securing the formingmembrane to the lay-up system. In some circumstances, vacuum can betransported using a nylon tube bag having a breather material inside.Also, in some cases, depending on the design and/or shape of theforming, small holes or orifices can be used to provide a fluidevacuation flow path from the tool surface 11 to an inside or hollowportion of the forming tool. These holes allow the forming membrane tobe drawn down more tightly around the forming tool surfaces, especiallyif the tool is very contoured.

Returning to FIGS. 5-7, these figures illustrate a time lapse schematicrepresentation of the forming process as the vacuum is applied and amechanical force 50 is applied to the lay-up system in the directionindicated to cause the second portion 81 of composite charge 20 to firstconform to the outer radius 44 and then to conform to inner radius 46and second upper surface 42 of forming tool 10. The release film 52 onthe composite charge 24 allows the second portion of the compositecharge to slide relative to the forming membrane and the second uppersurface of the forming tool. Because the uppermost surface 70 of thefairing bar 55 is above the height 59 of the second upper surface, theforming membrane is supported and prevents the second portion 81 of thecomposite charge 20 from being force downward onto the second uppersurface 42 by the forming membrane 24 as the vacuum pulls the formingmembrane downward as indicted by directional arrows 200. (see FIG. 5).As the process continues, the vacuum continues to pull the formingmembrane down upon the forming tool as shown in FIG. 6. The formingmembrane includes a first portion 98 and a second portion 99 that cometogether at the dotted line 101. Eventually the second portion of thecomposite charge contacts the second upper surface of the forming tool.As indicated by directional arrow 60, the second portion slides relativeto the upper surface and begins to conform to inner radius 46. Therelease film 52 and optional release film 53 on the second uppersurface, combined with the applied mechanical force 50, allows thesecond portion 81 to slide along the second upper surface 42 and toconform to the inner radius without wrinkling, bridging, orout-of-plane-buckling of the composite charge. (see FIG. 7).

Once the composite charge has fully conformed to the forming tool and inparticular conformed to the inner and outer radii of the forming tool,the heating of the composite charge is stopped and the composite isallowed to cool.

The now formed composite charge 210 (see FIG. 8) can be removed from theforming tool and placed on a curing tool 220. Of course, in somesituations it may be advantageous to lay-up the composite chargedirectly on a curing tool. In the event transfer to a curing tool isneeded, the release films used in the lay-up procedure remain with theformed composite charge. The release film is typically needed duringvacuum bagging curing in an autoclave. Removal of the formed compositecharge 210 may be achieved manually or alternatively, removal may beaccomplished in an automated manner with mechanical assistance or withother known manufacturing methods that utilize hands-free methods, suchas by use of robotic manipulators. Once on the curing tool 220 theformed composite charge 210 can be vacuum bagged, a vacuum drawn, andplaced in a curing apparatus 230, for example, an autoclave, asillustrated in FIG. 8. In some cases the formed composite charge willremain on the forming tool and sent directly to the curing apparatus230.

In some applications, it may be possible to use additional items of alayup assembly on base tool 10, such as without limitation, doublers,additional release films, and caul plates, along with the compositecharge. For example a composite doubler can be sandwiched between thecomposite charge and a carrier film. Similarly, a strip of release filmcan be sandwiched between the composite charge and carrier film alongthe edge margin on the film. This release film may aid in releasing andpeeling the carrier film away from the laid up composite charge. It mayalso be possible to employ a reinforcement in the layer of the compositecharge which allows some degree of deforming of the charge, but lessthan other, non-reinforced areas. The reinforcement may comprise, forexample and without limitation, cross-stitching in the composite charge.

The composite charge or pre-cure lamina 20 preferably is a pre-preg orpre-impregnated composite of fibers, where a matrix material, such asepoxy, is already present. The fibers often take the form of a weave andthe matrix is used to bond them together and to other components duringmanufacture. The matrix is only partially cured to allow easy handling.This is known as a B-Stage material and requires cold storage to preventcomplete curing. B-Stage pre-preg is always stored in cooled areas sinceheat accelerates complete polymerization. Composite structures orpre-cure lamina built of multiple plies of pre-pregs will typicallyrequire an oven or autoclave to cure the composite structure.

The lay-up system and associated laying-up method can employ one of morecarrier films to prevent contamination during transport of the compositecharge and to prevent the composite charge from touching anycontaminate. Preferably a deformable carrier film is used to support thecomposite charge during the lay-up of the composite charge and then totransport the charge to a cutting table. As the cutting table typicallyis not a contact surface, meaning the table should not directly contactthe pre-preg material, the carrier film will provide a barrier betweenthe pre-preg and the cutting table. The lay-up composite charge can thenbe cut using an ultra sonic knife to cut the large charge down tosmaller charge pieces that are then lay-up to the forming tool.

The composite charge may be lay-up on the carrier film so as to leaveone or more edge margins on the carrier film around the composite chargeto facilitate handling of the carrier film and/or attachment of hardwareor equipment to the carrier film that may be used to deform, manipulateand/or hold the carrier film during the layup process. ATL (AutomatedTape Lay-up) or FTLM (Flat Tape Laminating Machine) can often lay-upcharges on a carrier film. In one preferred arrangement, the compositecharge may be laid up manually by hand. In an alternative arrangement,the composite charge may be laid up using advanced fiber placement(“AFP”) or automated tape laying (“ATP”) manufacturing methods (or byany other known method) in the desired positions and orientations asdetermined during the composite laminate specification and design phase(See, e.g., FIG. 10 Step 432). The carrier film can also be useful forcontrolled and uniform or non-uniform deforming of composite chargebefore the lay-up process, and may also be used only as a carrier fortransporting the composite charge from an offline layup station to theforming tool 10. As used herein, “deform” and “deforming” refer tostretching and/or shearing of a ply material in one or more directions,including simple and compound curves, and within one or more planes.

FIG. 9 is an illustration of a perspective view of an aircraft 300 thatmay incorporate one or more composite laminates manufactured by one ofthe embodiments of the present disclosure. As shown in FIG. 9, theaircraft 300 comprises a fuselage 312, a nose 314, a cockpit 316, wings318 operatively coupled to the fuselage 320, one or more propulsionunits 320, a tail vertical stabilizer 322, and one or more tailhorizontal stabilizers 324. Although the aircraft 300 shown in FIG. 9 isgenerally representative of a commercial passenger aircraft, the one ormore composite laminates, as disclosed herein, may also be employed inother types of aircraft or air vehicles. More specifically, theteachings of the disclosed embodiments may be applied to other passengeraircraft, cargo aircraft, military aircraft, rotorcraft, and other typesof aircraft or aerial vehicles, as well as aerospace vehicles,satellites, space launch vehicles, rockets, and other aerospacevehicles. It may also be appreciated that embodiments of structures andmethods in accordance with the disclosure may be utilized in othertransport vehicles, such as boats and other watercraft, trains,automobiles, trucks, buses, or other suitable transport vehicles formedfrom or utilizing the composite laminates as disclosed herein.

Embodiments of the disclosure may find use in a variety of potentialapplications, particularly in the transportation industry, including forexample, aerospace, marine, automotive applications and otherapplication where thermoplastic composite tubular structures may beused. Therefore, referring now to FIGS. 10 and 11, embodiments of thedisclosure may be used in the context of an aircraft manufacturing andservice method 430 as shown in FIG. 10 and an aircraft 450 as shown inFIG. 11. Aircraft applications of the disclosed embodiments may include,for example, without limitation, the design and fabrication of compositelaminates fabricated by way of the lay-up methods and systems asdisclosed herein.

During pre-production, exemplary method 430 may include specificationand design 432 of the aircraft 450 and material procurement 434. As justone example, for the specification and design of the aircraft relatedcomposite laminates formed using complex shaped forming tools with innerand outer radii, such as a Z-shape forming tool disclosed herein, may bedetermined at this step. As just one example, at this step, it may bedetermined that complex shaped structural supports are needed requiringforming tools having male and female radii.

As another example, during this specification and design step, in oneparticular composite laminate arrangement, lay-up methods that userelease films prevent bridging or out-of-plane buckling of the compositecharge at inner radii of the forming tool may be determined. Inaddition, during this specification and design step, the use of use afairing bar may be selected with a configuration that supports theforming membrane such that the composite charge can conform precisely tothe male and female radii without buckling or bridging. As just anotherexample, at this design step, it may be determined that additional layupassembly items may be required for a specific composite part, such asdoublers, release films, and caul plates.

During production, component and subassembly manufacturing 436 andsystem integration 438 of the aircraft 450 takes place. As explained ingreater detail above, FIGS. 1-9 illustrate one preferred type of processsteps for fabricating composite laminate utilizing a combination ofrelease films and faring bar configuration in accordance with one aspectof the present disclosure. After such a component and subassemblymanufacturing step, the aircraft 450 may go through certification anddelivery 440 in order to be placed in service 442. While in service by acustomer, the aircraft 450 is scheduled for routine maintenance andservice 444, which may also include modification, reconfiguration,refurbishment, and so on.

Each of the process steps of method 450 may be performed or carried outby a system integrator, a third party, and/or an operator (e.g., acustomer). For the purposes of this description, a system integrator mayinclude without limitation any number of aircraft manufacturers andmajor-system subcontractors; a third party may include withoutlimitation any number of vendors, subcontractors, and suppliers; and anoperator may be an airline, leasing company, military entity, serviceorganization, and so on.

As shown in FIG. 11, the aircraft 450 produced by exemplary method 430may include an airframe 452 with a plurality of high-level systems 454and an interior 456. Examples of high-level systems 454 may include oneor more of a propulsion system 458, an electrical system 460, ahydraulic system 462, and an environmental system 464. Any number ofother systems may be included. Although an aerospace example is shown,the principles of the disclosure may be applied to other industries,such as the marine and automotive industries.

Systems and methods embodied herein may be employed during any one ormore of the stages of the production and service method 430. Forexample, components or subassemblies corresponding to production processmay be fabricated or manufactured in a manner similar to components orsubassemblies produced while the aircraft 450 is in service. Also, oneor more apparatus embodiments, method embodiments, or a combinationthereof may be utilized during the production stages 432 and 434, forexample, by substantially expediting assembly of or reducing the cost ofan aircraft 450. Similarly, one or more of apparatus embodiments, methodembodiments, or a combination thereof may be utilized while the aircraft450 is in service, for example and without limitation, to maintenanceand service 444.

The foregoing description of the specific embodiments will reveal thegeneral nature of the disclosure so others can, by applying currentknowledge, readily modify and/or adapt for various applications suchspecific embodiments without departing from the generic concept, andtherefore such adaptations and modifications are intended to becomprehended within the meaning and range of equivalents of thedisclosed embodiments. It is to be understood that the phraseology orterminology herein is for the purpose of description and not oflimitation.

The invention claimed is:
 1. A method for forming composite materials,the method comprising: providing a composite charge to a lay-up system,where the composite charge comprises upper and lower surfaces; applyingrelease film to the upper and lower surfaces of the composite charge;positioning a first portion of the composite charge across a first uppersurface of a forming tool having a first height measured from the firstupper surface to a bottom surface; overhanging a second portion of thecomposite charge over a second upper surface of the forming tool,wherein the second upper surface has a second height that is less thanthe first height; positioning a fairing bar to abut the forming tool,wherein the fairing bar has an uppermost surface, wherein the fairingbar is positioned relative to the forming tool such that the uppermostsurface is above the second upper surface of the forming tool; applyinga forming membrane over the composite charge, the release film, theforming tool, and the fairing bar; sealing the forming membrane around aperipheral edge of the lay-up system; causing, via applying a vacuum tothe lay-up system, a first portion of the forming membrane to conform tothe forming tool such that a portion of the second portion of thecomposite charge is brought into contact with a surface of the formingtool located between the first and second upper surfaces, and causing,via the applied vacuum, a remaining portion of the second portion of thecomposite charge to contact and slide along the second upper surface,wherein a second portion of the forming membrane (1) overhangs theforming tool and the fairing bar and (2) remains separated from thecomposite charge, the forming tool, and the fairing bar after the firstportion of the forming membrane is conformed to the forming tool suchthat the portion of the second portion of the composite charge isbrought into contact with the surface of the forming tool locatedbetween the first and second upper surfaces.
 2. The method of claim 1further comprising heating the composite charge.
 3. The method of claim2 wherein the composite charge is heated before applying the vacuum. 4.The method of claim 1, wherein applying the vacuum comprises applyingthe vacuum to conform a segment of the composite charge over an outerradius of the forming tool.
 5. The method of claim 1 further comprisingapplying a mechanical force to the second portion of the compositecharge to conform the second portion of the composite charge to an innerradius of the forming tool.
 6. The method of claim 5, wherein themechanical force is applied using an urging device that includes atleast one of a flexible tip, a spring board, a feather board, an elasticfairing, a compressible material, a pivoting pad, or a spring-loadedpad.
 7. The method of claim 1 further comprising forming the compositecharge to both an inner and outer radius of the forming tool where theforming membrane does not prevent the second portion of the compositecharge from sliding along the second upper surface of the forming toolto conform to the inner radius.
 8. The method of claim 1 furthercharacterized in that release film is applied to the second uppersurface of the forming tool prior to positioning the composite charge onthe forming tool.